Hydrogen cars leaking fuel... why?

[filmyak]

I went to the Wired Living Home tour today and was lucky enough to ride in the BMW Hydrogen Fuel car on the way back to the staging area.

The driver talked about the technology with us, and said one of the issues being worked on was the gas’s natural tendency to escape, as it’s lighter than air. That if you filled the hydrogen tank up and left the car parked for 3-4 days, the tank would be empty (hence it has a gasoline engine as well, for those situations).

Is it really that hard to build a container that can keep hydrogen gas from escaping? I was kind of surprised by this. What makes this gas so hard to hang on to in a car?

[Ale]

@filmyak

I went to the Wired Living Home tour today and was lucky enough to ride in the BMW Hydrogen Fuel car on the way back to the staging area.

The driver talked about the technology with us, and said one of the issues being worked on was the gas’s natural tendency to escape, as it’s lighter than air. That if you filled the hydrogen tank up and left the car parked for 3-4 days, the tank would be empty (hence it has a gasoline engine as well, for those situations).

Is it really that hard to build a container that can keep hydrogen gas from escaping? I was kind of surprised by this. What makes this gas so hard to hang on to in a car?

It has very tiny little molecules and you want to cram as much gas on as little a volume as possible; so the solution is to liquify it to a throughly uncomfrtable low temerature.
As good as it may be insulated heat is going to slowly get to the hydrogen making it boil, so the unused gas has to be vented to prevent a buildup of pressure inside the storage tank.

[Chrismoody]

I was going to make a joke about the Hindenburg but decided it was in bad taste…

[Derleth]

@Chrismoody

I was going to make a joke about the Hindenburg but decided it was in bad taste…

Then go to Florida and see all of the giant sea cows.

“Oh, the huge manatee!”

[filmyak]

@Ale

It has very tiny little molecules and you want to cram as much gas on as little a volume as possible; so the solution is to liquify it to a throughly uncomfrtable low temerature.
As good as it may be insulated heat is going to slowly get to the hydrogen making it boil, so the unused gas has to be vented to prevent a buildup of pressure inside the storage tank.

Ahhhhh. Yeah the driver did mention the storage was below -400 degrees.

As for the manatee joke, Derleth? :smack:

[Malacandra]

More on that “tiny little molecules” thing: the TLMs mean that it leaks like nothing on earth. When hydrogen’s stored in cylinders, the taps have special hydrogen-proof grease to minimise leakage - it would diffuse through ordinary grease. It’s that more than the lighter-than-air factor that’s troublesome. Indeed, being lighter than air means that at least any that escapes will fly away harmlessly, rather than form invisible explosive puddles inside the vehicle.

Chrismoody, apparently the dope they used on the Hindenburg’s fabric envelope had more to do with the disaster than the hydrogen did. If you have to be in an accident involving masses of highly inflammable gas, it might as well be gas that is trying to head skywards as fast as possible once it starts escaping.

[sturmhauke]

The paint on the Hindenburg’s skin was solid rocket fuel, they just didn’t know it at the time.

A more recent theory suggested by Addison Bain, former manager of NASA’s hydrogen program, was that the initial fire was not burning hydrogen. Hydrogen burns without much of a visible flame, but witnesses described the fire as extremely colorful. Bain thinks the doping solution used to stretch and waterproof the hull was responsible. The compound, a layer of iron oxide covered with coats of cellulose butyrate acetate mixed with powdered aluminum, is very similar to a mixture used to power solid fuel rockets. “The Hindenburg was literally painted with rocket fuel,” says Bain.